Master of Science / Department of Mechanical and Nuclear Engineering / William L. Dunn / The signature-based radiation-scanning (SBRS) technique relies on radiation detector responses, called “signatures,” and compares them to “templates”, to differentiate targets containing nitrogen-rich explosives from those that do not. This investigation utilizes nine signatures due to inelastic-scatter and prompt-capture gamma rays from hydrogen, carbon, nitrogen, and oxygen (HCNO) as well as two neutron signatures, produced when a target is interrogated with a 14.1 MeV neutron source beam. One hundred and forty three simulated experiments were conducted using MCNP5. Signatures of 42 targets containing explosive samples (21 of RDX and 21 of Urea Nitrate), and 21 containing inert samples were compared with the signatures of 80 artificial templates through figure-of-merit analysis. A density filter, comparing targets with templates of similar average density was investigated. Both high and low-density explosives (RDX-1.8 g cm-3 and Urea Nitrate-0.69 g cm-3) were shown to be differentiated from inert materials through use of neutron and gamma-ray signature templates with sensitivity of 90.5% and specificity of 76.2%. Density Groups were identified, in which neutron signature templates, gamma-ray signature templates or the combination of neutron and gamma-ray signature templates were capable of improving inert-explosive differentiation. figure-of -merit analysis, employing the best Density Group specific templates, differentiated explosive from inert targets with 90.5% sensitivity and specificity of over 85%.

Ransomware is a type of malware that hijack victims’ computers, by encrypting or locking corresponding files, and demanding the payment of some ransom in cryptocurrency for the restoration of the files. The last few years have witnessed a sudden rise in ransomware attack incidents, causing significant amount of financial loss to individuals, institutions, and businesses. In reaction to that, ransomware detection has become an important topic for research in recent years. Currently, there are three types of ransomware detection techniques available in the wild: static, dynamic and hybrid. Unfortunately, the current static detection techniques can be easily evaded by code-obfuscation and encryption techniques. Furthermore, current dynamic and hybrid techniques face difficulties to detect novel ransomware. In the current thesis, we present an upgraded dynamic ransomware detection model with two new sets of features: grouped registry key operation, and combined file entropy and file signature. We analyze the new feature model by exploring and comparing 3 different linear machine learning techniques: SVM, Logistic Regression and Random Forest. The proposed approach help achieves improved detection accuracy and provides the ability to detect novel ransomware. Furthermore, the proposed approach helps differentiate user-triggered encryption from ransomware-triggered encryption, which allows saving as many files as possible during an attack. To conduct our study, we use a new public ransomware detection dataset collected at the ISOT lab, which consists of 666 ransomware and 103 benign binaries. Our experimental results show that our proposed approach achieves relatively high accuracy in detecting both previously seen and novel ransomware samples. / Graduate

Konstant uppkoppling till internet idag är en självklarhet för många världen över. Internet bidrar till en global förbindelse som aldrig tidigare varit möjligt, vilken kan tyckas vara underbart i många avseenden. Dessvärre kan denna digitala förbindelse missbrukas och användas för ondsinta ändamål vilket har lett till behov av säkerhetslösningar som bland annat nätverks-intrångsdetektionssystem. Ett av de mest omtalade verktygen som är ett exempel på ett sådant system är Snort som studeras i denna studie. Utöver analysering av Snort, evalueras även olika signaturdatabasers detektionsförmåga av angrepp. Totalt exekverades 1143 angrepp från 2008-2019 och dessa utvärderades av tre Snort-versioner daterade 2012, 2016 och 2018. Varje Snort-version analyserade angreppen med 18 signaturdatabaser daterade 2011-2019 från tre olika utgivare. Resultaten visar att det stor skillnad mellan de olika utgivarnas signaturdatabaser där den bästa detekterade runt 70% av angreppen medan den sämsta endast detekterade runt 1%. Även hur Snort konfigurerades hade stor inverkan på resultatet där Snort med för-processorn detekterade omkring 15% fler angrepp än utan den. / For many people all over the world being constantly connected to the Internet is taken for granted. The Internet connects people globally in a way that has never been possible before, which in many ways is a fantastic thing. Unfortunately, this global connection can be abused for malicious purposes which have led to the need for security solutions such as network intrusion detection systems. One prominent example of such a system is Snort which is the subject of evaluation in this thesis. This study investigates the ability of signature databases for Snort to detect cyberattacks. In total, we executed 1143 attacks released between 2008-2019 and recorded the network traffic. We then analyzed the network traffic using three versions of Snort released 2012, 2016, and 2018. For each version, we used 18 different signature databases dated 2011-2019 from three different publishers. Our results show that there are a significant difference between the different publishers’ signature databases, where the best signature database detected around 70% of the attacks and the worst only detected around 1%. The configuration of Snort also had a significant impact on the results, where Snort with the pre-processor detected about 15% more attacks than without it.

Este trabalho faz uma análise crítica dos elementos jurídicos-tecnológicos de uma assinatura digital certificada digitalmente. O primeiro aspecto a ser abordado advém da verificação da competência para o desenvolvimento da atividade de certificação, em decorrência da natureza jurídica do certificado digital. Consoante se verificou, o certificado digital é o instrumento hábil a assegurar a autenticidade dos documentos eletrônicos por meio de uma assinatura digital. Dessa forma, equipara-se ao ato de reconhecimento de firma, atividade notarial desenvolvida pelos Cartórios Notariais, de acordo com a competência fixada no artigo 236 da Constituição da República Federativa do Brasil. Todavia, segundo regra presente na Medida Provisória 2.200-2/01, desde 2001 essa atividade vem sendo desenvolvida sob a competência do Governo Federal, através do Instituto Nacional de Tecnologia da Informação - ITI (Autoridade Certificadora Raiz da Infraestrutura de Chaves Públicas do Brasil. Como decorrência tem-se que a Medida Provisória 2.200-2/01 é inconstitucional, uma vez que não respeita regra de competência material fixada pela Constituição da República Federativa do Brasil para o desenvolvimento da atividade notarial. Sob um prisma tecnológico, têm-se que a ICP-Brasil, por meio de seu Comitê Gestor, fixa expressamente qual a tecnologia que deve ser empregada para a produção das assinaturas digitais. Neste caminho, até maio de 2006, entre outros, foi indicado o algoritmo criptográfico de função hash MD5 para a geração das assinaturas digitais com autenticidade e integridade garantidas por lei. Todavia, o MD5 perdeu sua utilidade em 2004, quando foi quebrado, ocasionando a possibilidade de fraudes, inclusive a geração de documentos eletrônicos forjados. Sem dúvida, a legislação brasileira vinha assegurando validade jurídica e força probante a documentos eletrônicos assinados com algoritmo criptográfico de função hash MD5 que poderiam ter sido forjados. Para que o documento eletrônico assinado digitalmente possa ser amplamente utilizado em relações sociais é preciso que regras jurídicas e tecnológicas sejam respeitadas, sob pena de se criar uma enorme insegurança social. / This work presents a critical analysis of the technology and law aspects of certified digital signatures, and their implementation in Brazil. We discuss and verify the competency rules that apply to the certification activity according to the legal nature of the digital certificate. A digital certificate is the instrument that secures the authenticity of an electronic document by means of a digital signature. According to the article 236 of the Brazilian Constitution, authenticity certifications are of exclusive competence of public notaries. Nevertheless, based on an under constitutional statute, digital certification has being conducted by the Federal Government thru its National Institute of Information Technology (Instituto Nacional de Tecnologia da Informação - ITI), who is responsible for the Brazilian public key root certification authority. We found that the statute that supports those activities (Medida Provisória 2.200-2/01) is unconstitutional, and therefore invalid and unenforceable, since it does not satisfy constitutional rules of material competency. Under a technology view, we find that the Managing Committee of the Brazilian Public Key Infrastructure explicitly defines the technology to be used in digital signatures. According to that ruling, until may 2006, among others, the MD5 hashing algorithm was used to generate digital signatures with statutory presumption of authenticity and integrity. Nevertheless, MD5 lost its technical usefulness in 2004, when it was broken, and became prone to fraud such as the generation of forged electronic documents. There is no doubt that Brazilian legislation gave legal value and probatory force to electronic documents signed using the already broken MD5 hashing algorithm that could very well had been forged. Digitally signed electronic documents can only be successfully used if legal rules and the technological aspects be fully understood and respected. Otherwise, the result will be high levels of uncertainty in law relations.

Os astrocitomas são os tumores cerebrais primários mais frequentes, dentre os quais, o glioblastoma multiforme (GBM) é o tipo mais agressivo, sendo classificado como astrocitoma de grau IV. O tratamento envolve remoção cirúrgica seguida de quimio e radioterapias, porém essa abordagem não é eficaz devido à alta resistência das células tumorais. Em um trabalho anterior, buscando caracterizar os mecanismos associados à esta característica, investigamos a expressão de genes de reparo de DNA em astrocitomas de diferentes graus. Foram encontradas alterações em 19 genes. Através da combinação destas alterações em todos os arranjos possíveis, definimos um grande conjunto de assinaturas de expressão gênica que foi utilizado como filtro para a busca de correlação em bancos de dados públicos. No total, 421 assinaturas foram associadas à redução na sobrevida dos pacientes, sendo que cinco dos genes (EXO1, NEIL3, BRCA2, BRIP1 e DDB2) foram isoladamente relacionados ao pior prognóstico. Notavelmente, DDB2 foi o único gene subexpresso a apresentar esta correlação, levando a um risco de morte aproximadamente três vezes maior. No presente estudo in vitro, após radiação ionizante, observamos que células com baixos níveis de DDB2 reparam mais rapidamente as quebras induzidas no DNA, saem mais facilmente da parada de ciclo na fase G2/M e se tornam ainda mais resistentes a este tratamento. Além disso, o silenciamento de DDB2 induziu o aumento dos níveis de Zeb1, um importante promotor da transição epitélio-mesênquima, bem como dos índices de invasão e migração celular. Estes dados mostram que a redução nos níveis de DDB2 induz um fenótipo mais agressivo, corroborando a correlação com pior prognóstico dos pacientes observado anteriormente. Tomados em conjunto, esses resultados sugerem que a função de DDB2 não está limitada ao âmbito do reparo de DNA, apontam uma potencial relação com o controle da transição epitélio-mesênquima e mostram que este gene possui papel fundamental no estabelecimento da agressividade e resistência de GBM. / Astrocytomas are the most common primary brain tumors. Glioblastoma multiforme (GBM) is the most aggressive type and is classified as grade IV astrocytoma. The treatment involves surgical resection followed by chemo and radiotherapies, however this approach is not effective due to the high resistance of tumor cells. In a previous work, to characterize the cellular mechanisms associated to this characteristic, we investigated the expression of DNA repair genes in samples of different astrocytoma grades. We found alterations in 19 genes. By combining these expression changes in all possible arrangements, a large set of gene expression signatures was defined and used as a filter to seek correlations in public databases. As a result, 421 signatures were associated with reduced patient survival. Among them, five genes (EXO1, NEIL3, BRCA2, BRIP1 and DDB2) were individually related to worse prognosis. Notably, DDB2 was the only down regulated gene to exhibit this correlation, making the risk of death approximately three times higher. In the present in vitro study, after ionizing radiation, we observed that cells with low levels of DDB2 are capable of faster DNA breaks repair, easily exit the G2/M arrest and become even more resistant to this treatment. Furthermore, DDB2 silencing enhanced the levels of Zeb1, an important promoter of the epithelial-mesenchymal transition, as well as the rates of cell invasion and migration. These data indicate that DDB2 knockdown leads to a more aggressive cell behavior, corroborating the association with worse prognosis previously observed. Taken together, these results suggest that DDB2 function is not limited to DNA repair, they point out its potential participation in epithelial-mesenchymal transition control and show that this gene might play a key role in GBM\'s aggressiveness and resistance.

O modelo aplicado neste trabalho está baseado em resultados experimentais usando dados de composição química dos fragmentos cerâmicos, aplicados à teste não paramétrico de Spearmann, análise de componente principal e análise discrimante. As amostras são fragmentos cerâmicos da Tradição Tupiguarani de sítios e amostras de solos da região central do Estado do Rio Grande do Sul. Os elementos químicos, Al, Ba, Ca, Cr, Fe, K Mn, Pb, Rb, S, Si, Sr, Ti, V e Zn foram determinados usando-se as técnicas de fluorescência de raios X por dispersão de energia (EDXFR). Os elementos, Ce, Cu, Gd, La, Nd, Pr, Sm, Th e Y por espectrometria de massas de alta resolução com fonte de plasma acoplado indutivamente (HR-ICP-MS). A partir destes resultados, foram propostas relações entre as características da cerâmica, os sítios estudados e a dispersão dos fragmentos nos diversos sítios. Observaram-se indícios de assinatura química da função da vasilha de ir ou não ao fogo. A maior dispersão é de vasilhas pequenas com tratamento de superfície não corrugada. Verificaram-se assinaturas químicas para o entorno dos rios Ijuí, Ibicuí-Vacacaí Mirim e Jacuí. / In this work a model based on experimental results using chemical composition data of the pottery sherds applied to Spearmann’s no parametric test, principal component analysis and discriminant analysis, was applied. The samples are soils and Tupiguarani Tradition pottery sherd from the central area of the Rio Grande do Sul State. The chemical elements , Al, Ba, Ca, Cr, Fe, K Mn, Pb, Rb, S, Si, Sr, Ti, V and Zn were determined by energy dispersive X-ray fluorescence (EDXFR) while Ce, Cu, Gd, La, Nd, Pr, Sm, Th and Y by high-resolution inductively coupled plasma mass spectrometry (HR-ICP-MS) techniques. Relationships among the pottery characteristics, studied sites and sherd dispersion in the several sites were proposed. Indications of chemical signature of the small pottery with function to go or not to the fire were observed. The largest dispersion is of small pottery with surface treatment no corrugated. The potteries chemical fingerprints from Ijuí River, Ibicuí-Vacacaí Mirim River and Jacuí River were verified.

Com o surgimento da criptografia de chave pública, muito esforço foi feito para a criação de protocolos de criptografia e de assinatura que fossem comprovadamente seguros contra indivíduos maliciosos. Existem várias definições de segurança, tanto para protocolos de criptografia como para protocolos de assinatura, e também existem vários modelos de adversários, que simulam um indivíduo malicioso tentando corromper o protocolo. A família de protocolos de assinatura Rabin possui os recordes de velocidade de vericação da assinatura, chegando a ser até 100 vezes mais rápida do que o RSA. Este trabalho apresenta uma redução eficiente de segurança no modelo do oráculo aleatório para uma variante do protocolo de assinatura Rabin descrito por Bernstein, onde não é necessário o uso de nenhuma função para geração de bits pseudo-aleatórios, o que torna o protocolo mais robusto. A redução apresentada é uma redução polinomial e eficiente do problema da fatoração de inteiros para o problema de quebrar o protocolo Principal Rabin-Williams B = 0. / With the development of public-key cryptography, many efforts were made to build encryption and signature protocols that were provably secure against malicious adversaries. There are many definitions of security for encryption and signature protocols, and there are many adversary models to simulate the behaviour of a malicious adversary against a given protocol. The Rabin family of signature protocols has the speed records for verification of signature, being up to 100 times faster than RSA. This work presents a tight security proof in the random oracle model for a variant of the Rabin signature protocol presented by Bernstein, that does not require the use of pseudo-random bits, making the protocol more robust. The proof presented here is a polynomially tight reduction for the problem of integer factorization to the problem of breaking the Principal Rabin-Williams B = 0 protocol.

This thesis established the cubature method developed by Gyurkó & Lyons (2010) and Lyons & Victor (2004) for the Heath–Jarrow–Morton (HJM) model. The HJM model was first proposed by Heath, Jarrow, and Morton (1992) to model the evolution of interest rates through the dynamics of the forward rate curve. These dynamics are described by an infinite-dimensional stochastic equation with the whole forward rate curve as a state variable. To construct the cubature method, we first discretize the infinite dimensional HJM equation and thereafter apply stochastic Taylor expansion to obtain cubature formulae. We further used their results to construct cubature formulae to degree 3, 5, 7 and 9 in 1-dimensional space. We give, a considerable step by step calculation regarding construction of cubature formulae on Wiener space.

This dissertation examines a twentieth-century lineage of writers and poets concerned with signatory inscription. By this, I mean the writing, tracing, branding, embossing, tattooing, or engraving of the name of a person or place onto various kinds of surfaces, as well as other forms of marking that approximate autography. My contention is that James Joyce's novels demonstrate an explicit, underexplored concern with signature and the different imaginary investments (erotic, legal, preservative) that accompany its presence in the world. In Joyce's wake, Samuel Beckett, Seamus Heaney, and Don DeLillo all produce texts that both engage with Joyce's novels and think carefully about the potential of the signature as a material object. My first chapter, 'James Joyce's Signatures', explores how nineteenth-century developments in graphology and forensic identification inherit ideas from the medicinal doctrine of signatures. I argue that this expanded sense of signature offers a unique perspective on Joyce's taxonomic representation, which questions the boundaries between a body of text and (non)human bodies. The presence of legal trials in Ulysses adds a forensic element to Joyce's signatory imagination. This element is taken to its logical extreme in 'Nausicaa', where scents, sounds, and impressions become bodily, as opposed to alphabetical, signatures - produced by humans, waves, and stones. The second chapter, 'Samuel Beckett and the Endurance of Names', continues this line of argument, showing how Beckett inherits Joyce's interest in autographic inscription, but employs it for different ends. While the epitaphic tradition relies upon hard materials such as stone and metal to preserve lettering, Beckett's interest in excrement ('First Love') and mud (How It Is) remaps inscription onto immanence. Rather than seeking immortality through lithic preservation, Beckett's characters yearn to 'return to the mineral state', to have their bodies subsumed and dispersed throughout a greater container. The third chapter, 'Seamus Heaney and the Phonetics of Place', turns from the signature of persons to the signature of places, from prose to poetry. Explicitly glossing poems like 'Anahorish', 'Toome', and 'Broagh' as inspired by Stephen Dedalus, Heaney performs a critical repatriation of Joyce's work. Joyce uses fictional, motivated relations between names and referents to construct a linguistic correlative for Stephen's youthful naivety - a technique that personalises his lexicon, privileging Stephen's own associations over those of nationality, language, or religion. Heaney, on the other hand, politicises this process, utilising phonetic association to forge imaginary correspondences between Irish place-names and the people and places they denote. The final chapter, 'Don DeLillo, Encryption, and Writing Technologies', examines the novels of Don DeLillo and his interest in signatory technologies. Drawing upon archival research conducted on the manuscripts of Americana, Ratner's Star and The Names, I show that Joyce influenced the composition of these texts to a greater extent than previously thought. In particular, DeLillo uses Joyce to think through the technological dimensions of writing, comparing older methods of inscription like boustrophedon to modern communication technologies via Ulysses.

Submitted by Filipe dos Santos (fsantos@pucsp.br) on 2016-11-21T12:42:51Z No. of bitstreams: 1 Ettore Alves Rigo De Lima Botteselli.pdf: 888307 bytes, checksum: 411881ed8c3efe41ba3e8de0dcbb80e2 (MD5) / Made available in DSpace on 2016-11-21T12:42:51Z (GMT). No. of bitstreams: 1 Ettore Alves Rigo De Lima Botteselli.pdf: 888307 bytes, checksum: 411881ed8c3efe41ba3e8de0dcbb80e2 (MD5) Previous issue date: 2016-09-29 / The current global dynamics demands fast and precise decisions. The technological development has allowed the creation and enforcement of digital documents. The electronic documents have their validity and enforcement recognized in several countries, including Brazil. One of the elements that enforced the consolidation of the electronic document in our law was the creation of the digital signature trough the digital certificates. That has granted to the digital documents legal certainty in regard to its authorship and origin. The usage of technological methods in corporate acts ensure a higher participation of the administration boards members and shareholders, besides the highest agility in decision making. The adoption of electronic mechanisms to hold such corporate acts, probably, would overcome the issues related to the absence, however the holding of corporate acts only in electronic format may, in some cases, create some uncertainty. The Brazilian corporate law sets forth several procedures and formalities which should be observed and, consequently, may compromise the validity and enforcement of corporate acts only in electronic format, especially the shareholders meeting. Notwithstanding such procedures and formalities, there is still a structure issue in regard to the registries of commerce, which may difficult the settlement of corporate acts only in electronic format / A dinâmica global atual exige decisões rápidas e precisas. O avanço tecnológico permitiu a criação e efetiva implementação de documentos digitais. Os documentos eletrônicos possuem a sua validade e eficácia reconhecida em diversos países, incluindo o Brasil. Um dos fatores que assegurou a consolidação do documento eletrônico em nosso ordenamento foi a criação da assinatura digital, por meio de certificados digitais. Isso assegurou aos documentos digitais segurança jurídica quanto a sua autoria e origem. A utilização de meios tecnológicos em atos societários assegura maior participação dos membros da administração e acionistas, além de maior agilidade na tomada de decisões. A adoção de mecanismos eletrônicos para a realização de tais atos, provavelmente, supriria questões relativas ao absenteísmo, no entanto, a realização de atos societários, essencialmente eletrônicos, pode, em alguns casos, gerar insegurança jurídica. A legislação societária brasileira estabelece diversos ritos e formalidades que devem ser observados e, portanto, podem comprometer a validade e eficácia dos atos societários essencialmente eletrônicos, em especial da assembleia geral eletrônica. Não obstante tais ritos e formalidades, ainda existe uma questão estrutural junto aos registros de comércio, que podem dificultar a implementação dos atos societários em formato totalmente eletrônico